For some NMR analyses, a sample is irradiated with radio frequency fields of two different frequencies at relatively high power levels, for example, 300-500 watts. It is important that good coupling to the sample be achieved at both frequencies. The efficiency of prior art probes is limited because of the size and magnetic restrictions for probe components. The present invention involves a double-tuned circuit which may be remotely disposed from the magnetic field which greatly reduces probe design problems because the size and magnetic restrictions for probe components are eliminated which results in enhanced sensitivity and a more efficient system.